This invention arose out of the need for a mechanism for advancing a rotatable turntable in an assembling machine but is not to be considered as being limited thereto. The rotatable turntable has a substantial mass and difficulty was encountered in accelerating and decelerating the table movement without effecting damage to the drive mechanism incorporated in the indexing mechanism during acceleration and deceleration thereof. In addition, and in view of the large mass of the turntable, it was necessary to eliminate the unusually high forces that would develop on conventional indexing mechanism which would engage the turntable at only one location thereon. In an effort to effectively drive the turntable, a positive connection has heretofore been provided between the drive and driven members. If an obstruction halting movement of the turntable occurred, the positive connection or the driven structure could seriously be damaged. As a result, a need arose for an indexing mechanism which would eliminate the aforementioned problems and provide for a durable and maintenance free operation.
Accordingly, it is an object of this invention to provide an indexing mechanism which uniformly applies a force to the driven member to effect an acceleration and deceleration of the turntable between indexed positions thereof.
It is a further object of this invention to provide an indexing mechanism, as aforesaid, wherein the connecting arrangement between the drive member and the driven member is mounted on the driven member and supported for movement relative thereto so that the drive member does not support the connecting arrangement connecting the drive member to the driven member.
It is a further object of this invention to provide an indexing mechanism, as aforesaid, wherein the driven member is driven at a velocity which is sinusoidal in nature so that the stresses applied to the supporting structure for the turntable is minimized during acceleration and deceleration thereof.
It is a further object to provide an indexing mechanism having a built in slip clutch, which clutch protects the indexing mechanism and the driven members in case of the appearance of outside members which would tend to inhibit the indexing of the driven member and consequently cause damaging or distructive forces to be applied to the indexing mechanism or the driven member.
It is a further object of the invention to provide an indexing mechanism, as aforesaid, wherein the spacing between indexed steps can be easily altered, the direction of movement of the driven member can be easily altered so that the indexing mechanism is adaptable to use with many different type work situations requiring an indexing operation.
It is a further object of this invention to provide an indexing mechanism as aforesaid, which is durable and essentially maintenance free.